The present invention relates to a semiconductor device and a method for manufacturing the same. More particularly, the present invention relates to a semiconductor device including a metal line and a method for manufacturing the same.
Semiconductor devices are manufactured to operate according to their assigned purposes through depositing/etching material on a silicon wafer and doping of impurities into a predetermined region within a silicon wafer. A representative example of a semiconductor device is a semiconductor memory device. The semiconductor memory device includes a large number of elements (e.g., transistors, capacitors, and resistors) in order to perform an assigned purpose. The respective elements are coupled together through conductive layers to exchange data or signals.
As the fabrication technologies of semiconductor devices have been developed, many efforts have been made to manufacture a larger number of chips on a wafer by increasing the integration density of semiconductor devices. Accordingly, a critical dimension (CD) in a design rule is gradually reduced in order to increase the integration density. Furthermore, semiconductor devices are increasingly required to operate at a higher speed and reduce power consumption.
In order to increase the integration density, it is necessary to reduce the sizes of elements inside the semiconductor devices and reduce the lengths and widths of interconnections which couple the elements together. Moreover, the resistances of interconnections must be small so that electric signals can be transferred with minimal loss within the semiconductor devices through interconnections having narrow widths.
Generally, in a semiconductor device, metal lines are formed on various layers in order to electrically couple elements or interconnections. A contact plug is then formed in order to couple an upper metal line to a lower metal line. Recent studies have been conducted to use copper (Cu), which has a low resistance, as a metal line material, or reduce a pattern density of a metal line itself.